Access assembly with ribbed seal

ABSTRACT

A ribbed seal for use in endoscopic surgery is intended to be incorporated into a cannula assembly to limit the escape of insufflation gasses from a body cavity by forming a fluid-tight seal around an instrument inserted through the cannula assembly. The ribbed seal includes a relatively flat, disk shaped elastomeric overmold portion having a central aperture sized slightly smaller than the instrument such that the aperture must expand to accommodate the instrument. Molded together with the elastomeric overmold is an array of slender ribs disposed about the aperture. The ribs are designed to be relatively flexible under lateral loads. This allows the seal to bend easily as the surgical instrument is inserted through the aperture thereby maintaining a low insertion and glide force. On the other hand, the ribs are designed to be relatively rigid when loaded axially. This rigidity provides robust radial support for the instrument inserted through the center of the array of ribs. The seal performs a centering function for the instrument due to its combined elasticity and stiffness. Finally, the seal also allows for an instrument to be removed easily while maintaining the required atmospheric integrity.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims the benefit of and priority to U.S.Provisional Application Ser. No. 60/931,253 filed on May 22, 2007, theentire contents of which are incorporated herein by reference.

BACKGROUND

1. Technical Field

The present disclosure relates generally to a seal for use in endoscopicsurgery adapted to maintain a fluid-tight connection about an instrumentinserted through a cannula. In particular, the disclosure relates to aseal member having elasticity and rigidity characteristics whichfacilitate its effective use.

2. Background of Related Art

Minimally invasive surgical procedures are performed throughout the bodyand generally rely on obtaining access to an internal surgical sitethrough a small incision made in the skin of a patient. A cannula is anarrow tube, typically 5 to 13 mm in diameter, which is partiallyinserted into the small incision in the skin to hold the incision open.The cannula provides a portal or conduit between the surgical site andthe exterior of the patient's body through which a surgeon may introducethe various surgical instruments required by the desired procedures.

A cannula assembly typically includes components adapted to maintain aseal across its opening at all times, i.e., prior to, during andsubsequent to the introduction or removal of a surgical instrument. Theneed for a fluid-tight seal is apparent when considering laparoscopicprocedures in which an insufflation gas, usually carbon dioxide, isintroduced into the patient's abdomen under a slight pressure toseparate the abdominal wall from the vital organs. The inflation of theabdominal cavity provides a space where a surgeon may introduce viewingequipment or maneuver instruments into position. The fluid-tight seal isneeded in this context to prevent the escape of insufflation gas tomaintain this viewing and working space.

A dual seal system may be used to prevent the escape of insufflationgas. A first type of “cannula” seal serves to provide the seal in theabsence of an instrument, but is usually defeated as soon as aninstrument is introduced. A second type of “instrument seal” is capableof making a fluid-tight connection with the instrument, but is usuallydefeated as soon as the instrument is withdrawn. Placing an instrumentseal proximally in relation to a cannula seal will allow the two sealsto cooperate to seal the cannula at all times. A flapper valve may beused as a cannula seal of the first type. This type of seal has a flapwhich normally closes the passageway through a cannula, but is forced topivot open by the distal end of an instrument. The flap may be biased bya spring to close once the surgeon withdraws the instrument. Anothertype of self-closing valve used for this purpose is an elastomericduckbill valve. This type of valve closes with the assistance of thepositive pressure inside an insufflated body cavity which forces thedistal faces of the duckbill into sealing abutment with each other. Asdiscussed above, a flapper valve, a duckbill valve or other type ofcannula seal typically will not prevent fluid losses once an instrumentis in place within the cannula. Accordingly, an instrument seal of thesecond type is provided. A simple type of conventional instrument sealincludes a relatively flat elastomeric member with an aperture sizedslightly smaller than the instrument to be introduced. The elastomericmember stretches and bends to expand the aperture to accommodate theinstrument.

An effective instrument seal will exhibit several characteristics, a fewof which are listed here. First, of course, is the ability to maintain afluid-tight connection with a surgical instrument as the instrument isbeing used. A surgeon will likely advance the instrument distallythrough the aperture of the instrument seal, manipulate the instrumentwith both radial and angular movements, and finally withdraw theinstrument. Through all of this movement, the instrument seal must beflexible enough to allow the aperture to move and reshape itselfappropriately to maintain the necessary fluid-tight connection. Second,it is important that the instrument seal not hinder the efforts of thesurgeon in advancing and withdrawing the instrument. There is a frictionforce associated with moving the instrument while it is in contact withthe aperture of the instrument seal. This friction force is sometimescalled an insertion force or glide force and must be low enough suchthat manipulating the instrument is not awkward for the surgeon. Also,an effective instrument seal will provide radial support for aninstrument. Adequate radial support will aid in stabilizing theinstrument so a surgeon need not direct too much attention to holdingthe instrument in position while performing the surgical procedures.Additionally, it is important that the instrument seal have memory toreturn to its original shape and position after use. This feature canfacilitate the insertion of subsequent instruments. Finally, because asingle surgical procedure will often require many instruments dissimilarsize, an effective instrument seal will be able to accommodateinstruments having a wide range of sizes.

Design considerations intended to enhance some of these instrument sealcharacteristics may also enhance others. For example, features designedto give an instrument seal radial rigidity to provide radial support toan instrument are also likely to be helpful in providing an instrumentseal with memory. On the other hand, many of these design considerationscompete with one another. In particular, to provide an instrument sealwith a sufficient closing force to maintain a fluid-tight connectionwith an instrument, an elastomeric member may be provided which has anincreased cross sectional thickness about the aperture. The increasedsurface area in contact with the instrument will enhance the sealingcharacteristics, but at the same time will adversely affect theinsertion and glide forces. An instrument seal designed to be extremelyflexible in order to minimize insertion and glide forces may beineffective in providing radial support to an instrument. Accordingly,an effective instrument seal is capable of balancing the competingdesign goals to allow for an effective fluid-tight seal to be maintainedwhile not providing a difficult or awkward use.

SUMMARY

The present disclosure describes a seal mounted within a cannulaassembly adapted to engage a surgical instrument to permit sealed entryof the instrument into an internal tissue site. The seal includes afirst elastomeric member having a passageway for the instrument along aseal axis and a second member at least partially embedded within thefirst member to urge the instrument into general alignment with the sealaxis. The second member includes an annular element and at least one ribextending inwardly from the annular element toward the seal axis.

In other embodiments, the seal may include a radial array of ribsextending inwardly from the annular element which may cooperate to urgethe instrument into alignment with the seal axis. Furthermore, the sealmay be a septum seal having a generally planar configuration with anaperture for passage of the instrument. The rib or ribs included on theseal may be tapered such that the width decreases toward the seal axis,or the rib or ribs may be generally diamond shaped such that the widthdecreases toward the annular element as well as toward the seal axis.Openings may be included on a rib to enhance its flexibility. The ribsmay include a free end which is adjacent to the passageway through thefirst elastomeric member, and the free end may be substantially spacedfrom the passageway. An alternative rib shape involves a fork such thata first leg of the rib extends inwardly from the annular element andsecond and third legs extend inwardly from the first leg. The second andthird legs of a forked rib may be spaced from one another and includeportions which are generally parallel.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the presentdisclosure and, together with the detailed description of theembodiments given below, serve to explain the principles of thedisclosure.

FIG. 1 is an exploded perspective view of a ribbed seal memberincorporated into a cannula assembly;

FIG. 2 is a top view of a ribbed seal member;

FIG. 3 is a cross-sectional view of the ribbed seal member of FIG. 2taken along section lines A-A of FIG. 2;

FIG. 4 is an enlarged cross-sectional view of the area of detail B asindicated in FIG. 3 depicting the rib to overmold connection at theouter portions of the ribbed seal;

FIG. 5 is a view similar to FIG. 4 depicting an alternate embodiment ofthe rib to overmold connection of the ribbed seal;

FIG. 6 is a partial cross-sectional view of the upper and lower ribbedseal housings of FIG. 1 containing a ribbed seal and an instrumentpartially inserted;

FIG. 7 is a view similar to FIG. 6 depicting a ribbed seal making afluid-tight connection about an instrument; and

FIG. 8A-8X depict alternate embodiments of the ribbed seal with variousrib geometries and rib array configurations.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present disclosure contemplates the introduction into a person'sbody of all types of surgical instruments including clip appliers,graspers, dissectors, retractors, staplers, laser fibers, photographicdevices, endoscopes and laparoscopes, tubes, and the like. All suchobjects are referred to herein generally as “instruments.” In thedrawings and in the description which follows, the term “proximal,” asis traditional, will refer to the direction toward the operator or arelative position on the surgical device or instrument which is closerto the operator, while the term “distal” will refer to the directionaway from the operator or relative position of the instrument which isfurther from the operator.

Referring initially to FIG. 1, the ribbed seal 100 of the presentinvention is shown as a component of cannula assembly 10. The distal end(not shown) of cannula 12 is intended to be inserted into a body cavitythrough a small cut made in the skin to provide a portal or conduit intothe body cavity. Enlarged proximal portion 16 of cannula 12 may containinternal threads for attachment to external threads disposed on thedistal end of lip seal body 22.

Lip seal body 22 includes port 24 through which an insufflation gas maybe inserted and directed through cannula 12 into the body cavity. Lipseal body 22 also includes an internal shoulder 28 upon which lip seal26 rests. Lip seal 26 includes a narrow slot 30 which is normally biasedto a closed position but may be opened by inserting an instrument fromthe proximal side. A snap cap 32 may be connected by any conventionalmeans to lip seal body 22 enclosing lip seal 26 therein.

An elastomeric ring 34 is disposed about the proximal portion of snapcap 32 to provide for a snug fit with adapter 36. Adapter 36 may beformed to take any shape necessary depending on the type of equipment tobe attached to its proximal end. Here it is shown having an elongatedsubstantially rectangular shape with mating shoulder 38 on its proximalend. Mating shoulder 38 is adapted to make a disengageable, butfluid-tight connection to ribbed seal lower housing 42. The connectionis preferably fluid tight to assist in the prevention of insufflationgas leaks, but also disengageable to allow the instrument seal to beremoved during a surgical procedure. The removal of the instrument sealfrom a dual seal system allows for an exchange to be made for a sealmore suitable for the upcoming steps of the surgical procedure, or theremoval of the instrument seal may simply facilitate the removalirregularly shaped body tissue from the body cavity.

A circular opening 46 is disposed on the proximal end of lower ribbedseal housing 42. Ribbed seal 100 is positioned within the circularopening 46 and enclosed by the connection of upper ribbed seal housing48 to lower ribbed seal housing 44 by any conventional means. Here snapposts 52 are provided which interface with holes 54 to hold the twohousing components together.

Referring now to FIG. 2-5, the ribbed seal 100 of the present inventionwill be described in greater detail. Ribbed seal 100 is depicted as aseptum seal. Septum seals are characterized generally as elastomeric andplanar in configuration. Ribbed seal 100 includes two main components.First, is an elastomeric overmold 101 which has a central aperture 102for the sealed reception of surgical instruments. Overmold portion 101is substantially flat and extends radially from the aperture. Next, thesecond main component is a rib array 200 having plurality of individualribs 201. Rib array 200 and overmold 101 may be composed of the samematerial, but are more preferably each composed of separate materialsselected to have characteristics advantageously affecting the sealperformance.

The ribs 201 are preferably formed from a material which will allow themto maintain an axial rigidity while bending easily under a lateral load.A suitable material may be a rigid plastic such as polypropylene whichwill bend appropriately when configured to have a slender geometry. Theovermold portion 101 is preferably formed from a thermoplastic elastomerwhich will bend and stretch easily upon the insertion of an instrumentand will allow the aperture 102 to expand to create a fluid-tight sealaround variously sized instruments. If the materials are chosenappropriately, the two components of the ribbed seal 100 may be combinedto form a single inseparable unit without adhesives despite havingdisparate materials. This may be accomplished by using a co-molding orovermolding process. Such a process may involve co-injection wherein thetwo materials are injected into a mold at about the same time andallowed to set together. Alternatively, an insert molding process can beused where a first material is injected into a mold cavity and allowedto at least partially set, after which the cavity is modified toaccommodate the second material. In either case, the materials can beselected such that a strong bond is created between the two materialswithout the need for an adhesive. Processes other than injection moldingmay be used to form and combine the components as the particularmanufacturing process is not essential to the invention.

Ribbed seal 100 defines a maximum outer dimension and aperture 102defines a minimum internal dimension. Ribs 201 are disposed radiallyabout aperture 102. The length L of each rib is its longest dimensionwhich extends radially with respect to ribbed seal 100. Each rib 201also has a maximum width W and a height H. The width extends in adirection perpendicular to its length and parallel to the overmold 101while the height extends in a direction perpendicular to both the lengthand the width. The ribs 201 are connected to one another by outerannular rim 202 around the outer periphery of the array. The annular rim202 may be molded simultaneously with ribs 201 and from the samematerial. This will allow the ribs to be connected during manufacturingbefore the overmold portion 101 is applied to facilitate placement ofthe rib array into a second mold for application of the overmold portion101. As depicted in FIG. 4, the overmold 101 may be entirely flat,having a uniform thickness extending to the outer most surface of theannular rim 202. The overmold 101 is attached to the ribs only alongtheir lower face 211. Selecting a relatively rigid material for theannular rim 202 can provide a more rigid structure to the ribbed seal100. Annular rim 202 may be partially formed from the overmold materialas shown in FIG. 5. Such a configuration can provide an outer seal tohelp prevent the leakage of insufflation gasses around the outerperiphery of the circular opening 46 of the lower ribbed seal housing42. The annular rim 202 may also provide an upper clamping surface 210,best seen in FIG. 6 or 7, which may be positioned to abut upper ribbedseal housing 48 such that ribbed seal 100 is held securely between upperand lower ribbed seal housings 42, 48. The ribs 201 have a secured end209 adjacent to the annular rim 202 and an opposite free end 208. Ribs201 also have a lower face 211 adjacent to the overmold 101 and anopposite upper face 210.

The geometry of ribs 201 depicted in FIG. 2 is adapted to facilitate theinsertion and withdrawal of an instrument from a cannula. Each rib 201is connected to the annular rim 202 by a reduced profile arm 203 whichhas a width less than the width of the rib at its secured end 209. Ribs201 are generally diamond shaped having both an interiorly directedtaper 205 and an exteriorly directed taper 204. Also included arecentral bore 207 and a pair of minor bores 206. Bores 206, 207 mayextend through the rib to the lower face 211 as shown, or may terminateat any particular depth. Each of these geometric features is intended toprovide stress relief and concentrate bending in certain areas. When aninstrument 300 is inserted into the upper seal housing 48, as can beseen in FIG. 6, and the first contact is made with the overmold 101, theribbed seal 100 is substantially flat. The ribs 201 are thereforeinitially loaded in a purely lateral direction. Because the ribs areconfigured to bend easily, the instrument may be inserted without theapplication of much force. However, when the instrument 300 is ready forremoval, the ribbed seal 100 is no longer substantially flat as can beseen in FIG. 7. The ribs 201 will be pivoted distally and the ribbedseal 100 will have assumed a shape approximating a cone to accommodatethe instrument 300. In this configuration, when the instrument 300 iswithdrawn in a proximal direction there is a significant axial componentto the loading of the ribs. Because the ribs are configured to be stiffin buckling to provide radial support for the instrument, ribs will havean inherent tendency to resist the withdrawal of an instrument. Thegeometry of the rib array as described above can provide strategicallylocated bending zones to ease instrument withdrawal. This may beaccomplished by selectively combining any of the geometric features asdepicted in FIG. 8.

FIGS. 8A-C demonstrate that the number of ribs in the rib array alongwith the rib width may be varied to produce a seal member with thedesired characteristics for a particular application. A greater numberof more slender ribs may bend more easily than fewer but wider ribswhile maintaining the necessary radial support characteristics. FIGS.8E-G depict the use of a reduced profile arm to connect the ribs to theannular rim. This will provide a zone of increased flexibility near theannular rim. FIGS. 8I-K depict the use of an interiorly directed taperto increase flexibility near the aperture. FIGS. I and J also depict theuse of exteriorly directed tapers to increase flexibility in regionsapproaching the annular rim. FIGS. 8M-O depict how the rib length may bevaried to provide robust radial support at different diameters withinthe seal member. The free ends of the ribs define a diameter ofincreased radial support which may be positioned to accommodatevariously sized instruments. FIGS. 8Q-S depict triangularly shaped ribshaving only an interiorly directed taper and a full profile connectionto the annular rim. FIGS. 8U-W depict ribs having a forked profile witha first leg extending from the annular rim and second and third legsextending from the first leg in a substantially spaced and parallelmanner. Finally, FIGS. 8D, H, L, P, T and X depict the use of boreswithin the ribs to provide zones of increased flexibility.

Although the foregoing disclosure has been described in some detail byway of illustration and example, for purposes of clarity orunderstanding, it will be obvious that certain changes and modificationsmay be practiced within the scope of the appended claims.

1. A surgical portal apparatus for permitting access to a tissue site,which comprises: a portal member dimensioned for positioning within bodytissue, the portal member having a passageway for providing access to atissue site and to permit introduction of a surgical object used inperforming a surgical procedure adjacent the tissue site; and a portalseal mounted relative to the portal member and defining a seal axis, theportal seal including a first member comprising an elastomeric materialand an inner surface defining a passage to permit passage of thesurgical object generally along the seal axis and being adapted toestablish a substantial sealed relation with the surgical object, and asecond member at least partially embedded within the first member, thesecond member including an at least partial outer annular element and aplurality of independent ribs indirectly connected to the at leastpartial outer annular element and extending inwardly toward the sealaxis, adjacent independent ribs being in spaced relation and having freeends spaced from the inner surface of the first member, each independentrib being disjoined and free from direct interconnection with the otherindependent ribs, whereby the ribs are capable of movement duringinsertion of the surgical object independent of an adjacent rib, theindependent ribs dimensioned and arranged to bias the surgical object ingeneral alignment with the seal axis.
 2. The surgical portal apparatusaccording to claim 1 wherein the ribs are adapted to cooperate to biasthe surgical object in general alignment with the seal axis.
 3. Thesurgical portal apparatus according to claim 2 wherein the ribs areadapted to articulate relative to the at least partial annular elementupon introduction and removal of the surgical object.
 4. The surgicalportal apparatus according to claim 1 wherein the portal seal is aseptum seal defining an aperture, the aperture being the passage.
 5. Thesurgical portal apparatus according to claim 1 wherein the at least onerib includes a tapered segment, the tapered segment defining a widthdecreasing toward the seal axis.
 6. The surgical portal apparatusaccording to claim 1 wherein the at least one rib includes anintermediate segment and first and second opposed tapered segmentsextending from the intermediate segment, the first tapered segmentdefining a width decreasing toward the seal axis, the second segmentdefining a width decreasing toward the at least partial outer annularelement.
 7. The surgical portal apparatus according to claim 1 whereinthe at least one rib defines an opening therethrough to enhanceflexibility of the at least one rib.
 8. The surgical portal apparatusaccording to claim 1 wherein the at least one rib defines a free endadjacent the passage of the first member of the portal seal.
 9. Thesurgical portal apparatus according to claim 8 wherein the free end ofthe at least one rib is spaced from the passage of the first member ofthe portal seal.
 10. The surgical portal apparatus according to claim 1wherein the at least one rib includes a first leg connected to the atleast partial annular element and second and third legs dependingrelative to the first leg toward the seal axis.
 11. The surgical portalapparatus according to claim 10 wherein the second and third legs arearranged in spaced and generally parallel relation.
 12. The surgicalportal apparatus according to claim 1 wherein the independent ribs aredimensioned to extend in general orthogonal relation with the seal axisin the absence of a surgical object within the passage of the seal. 13.The surgical portal apparatus according to claim 12 wherein the firstmember of the seal is substantially flat.
 14. The surgical portalapparatus according to claim 1 wherein the ribs of the second member ofthe seal each comprise a material different from the elastomericmaterial of the first member of the seal.
 15. The surgical portalapparatus of claim 1, wherein at least one of the plurality ofindependent ribs is indirectly connected to the at least partial outerannular element via an arm.
 16. A surgical portal apparatus forpermitting access to a tissue site, which comprises: a portal memberdimensioned for positioning within body tissue, the portal member havinga passageway for providing access to a tissue site and to permitintroduction of a surgical object used in performing a surgicalprocedure adjacent the tissue site; and a portal seal mounted relativeto the portal member and defining a seal axis, the portal seal includinga first member comprising an elastomeric material and an inner surfacedefining an aperture to permit passage of the surgical object generallyalong the seal axis and being adapted to establish a substantial sealedrelation with the surgical object, and a second member at leastpartially embedded within the first member, the second member includingan outer annular element and a plurality of separate and distinct ribsindirectly connected to the outer annular element and extending inwardlytoward the seal axis, adjacent ribs being arranged in radial spacedrelation and having respective free ends spaced from the inner surfaceof the first member, each rib being devoid of any direct interconnectionwith any adjacent ribs whereby the ribs are capable of movement duringinsertion of the surgical object independent of an adjacent rib.
 17. Thesurgical portal apparatus according to claim 16 wherein the ribs includetapered segments.
 18. The surgical portal apparatus according to claim16 wherein the ribs are dimensioned to extend in general orthogonalrelation with the seal axis in the absence of a surgical object withinthe aperture of the first member of the seal.
 19. The surgical portalapparatus according to claim 18 wherein the first member of the seal issubstantially planar.